Process for the manufacture of porous coatings and sheet materials on the basis of polyvinylchloride



United States Patent 3,520,836 PROCESS FOR THE MANUFACTURE OF POROUS COATINGS AND SHEET MATERIALS ON THE BASIS OF POLYVINYLCHLORIDE Paul Spielau, Spich, Germany, assignor to Dynamit Nobel Alrtiengesellschaft, a German corporation No Drawing. Filed Mar. 7, 1967, Ser. No. 621,738 Claims priority, application Germany, Mar. 8, 1966, D 44,531; Oct. 2, 1965, D 48,338 Int. Cl. C08f 47/10 US. Cl. 2602.5 3 Claims ABSTRACT OF THE DISCLOSURE Process for manufacturing porous coatings and sheet materials suitable for use, for example, as synthetic leathers which comprises forming a film with or without an underlying support from mixtures composed of polyvinylchloride polymers or coplymers which have been obtained by emulsion polymerization, having an average grain size of 30 to 100 microns and a packed density of at least 0.5 g./ml., a plasticizer and about 2 to percent of an aqeuous ammonium carbonate or bicarbonate solution and optionally such materials as fillers and coloring agents. The ammonium carbonate or bicarbonate is used in an amount of 0.2 to 3 weight percent and preferably 0.5 to 1.5 weight percent referred to the solids present in the mixture. The spread mixture, as for instance, the mixture spread on a support such as a sheet of textile is then set at an elevated temperature.

This invention relates to porous coatings and sheet materials on the basis of polyvinylchloride and methods for their production. More particularly, this invention relates to porous coatings and sheet materials on the basis of polyvinylchloride permeable to air and moisture and accordingly suitable for use as synthetic leathers and methods for their production.

Artificial leather prepared from plasticized polyvinylchloride, has been in use for some time and has the disadvantage, as compared With leather derived from animal hides, that it is impermeable to air and water vapor. At tempts have been made to eliminate this disadvantage as for example by incorporating additives into the sheet material and then washing them out again, or by mechanically piercing the sheet. A disadvantage of the former procedure is that relatively expensive washing processes are required, and of the 'latter procedure, that products are obtained which are not the equal in quality of natural leather as regards permeability. Further a sufiiciently fine pore structure cannot be imparted to the sheet by adding to polyvinylchloride having average grain sizes of about 0.1 to 3 microns (such as used in the preparation of coating compositions) foaming or pore forming agents which produce gases under the action of temperature, such as, for example, azodicarbonamide or aziosobutyronitrile.

According to one known process (US. Pat. 2,864,777), a porous film is obtained by working polyvinylchloride having an average grain size of 0.2 to 2 microns with a plasticizer and water. According to other methods (U.S. Pats. 2,946,095 and 2,960,728), aqueous aminoplasts or phenoplasts and water-binding fillers are used. -In this manner, sheets are obtained which, for example, permit the passage of up to 200 liters of air per hour per square decimeter in thicknesses of 0.38 mm. The determination of air-permeability gives no indication of the quality of a porous sheet material, since it does not allow for any distinction between a sheet having fine pores uniformly distributed over a given area and a sheet having few large pores irregularly distributed over the same area. Thereice fore the decision as to the quality of a porous sheet material must be based not only on air-permeability but also on water-permeability or ink-permeability.

According to another patent (German Pat. 967,403), a porous sheet material is manufactured by adding polyvinylchloride, in a mixture with a plasticizer and a filler, an organic material that is capable of swelling, such as starch, and also, if desired, a foaming agent. The sheet thus produced, however, has the disadvantage that it has a sticky and consequently easily soiled surface.

In contrast to polyvinylchloride having an average grain size of about 0.1 to 3 microns, polyvinylchloride having an average grain size of about 30 to 100 microns have hitherto not assumed any importance in the art of fabric coating because of their substantially inferior fiow properties. This is apparent from the following table in which time measurements which were obtained using a Ford pouring beaker DIN 53,211 having an 8 mm. nozzle are set out.

TABLE 1 Ford Seconds PVC 70 parts DOP 1 Grain Mannsize, 45 PVC (tradenarne) iacturer microns 30 35 40 parts 1 DOP=Dioctylphthalate. 2 All grain-sizes between these limits can be present. 8 Did not flow.

1 Wacker-Chemie, see Waeker-prospect Nr. 2603.639 0. K. 2 Farbw. Hoechst.

3 Chem. Werke Htils, see sheet-collection Vestolit, July 1966.

4 Goodrich, U.S.A, see Gem-prospect", fourth edition, Ian. 1957.

5 Dynamit Nobel, the numbers of PVL E60, E67 and E69 are K- Werte" a unit of measurement of the viscosity in an opganie solvent.

This class of emulsion polyvinylchloride which forms coating compositions poorly if at all are the basis of the coating compositions in accordance with the invention.

It is, therefore, an object of the present invention to provide a method of improving the properties of emulsion produced polyvinylchlorides having a grain size of from 30 to microns wherein the coatings or sheet materials produced therefrom, are greatly improved as compared to prior coatings or sheet materials.

Another object of the invention is to provide a method for treating emulsion produced polyvinylchlorides having a grain size of from 30 to 100 microns as to improve the permeability to water and air of the sheet materials produced therefrom.

A further object of the invention is to provide a method for treating emulsion produced polyvinylchlorides having a grain size of from 30 to 100 microns whereby finely and uniformly porous sheet materials are produced.

Various other objects, advantages and features of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure.

The instant invention resides in a process which eliminates or substantially minimizes the above-discussed problems with a resulting production of porous coatings and sheet materials having a satisfactory permeability to air and water i.e., moisture. Broadly speaking, the process comprises the manufacture of porous coatings or sheet materials, such as artificial leather from water-containing coating compositions on the basis of polyvinylchloride or copolymers thereof, by forming the coating compositions or mixtures from polyvinylchloride polymers produced by the emulsion polymerisation process having an average grain size of 30 to 100 microns and a packed density of more than 0.5 g./ml., plasticizers and, optionally, fillers and colorants and approximately 2 to 15 percent aqueous solutions of ammonium carbonate or The densities of the sheet materials made according to the invention amount to from 0.6 to 0.9 g./ml., depending on the plasticizer and filler content.

The porous films manufactured in accordance with the invention can be self-supporting or can be supported ammonium bicarbonate, wherein the said carbonates 5 on t til mattings, paper or i f b i d are amount to 0.2 to 3 percent, and preferably 0.5 to 1.5 duced by spreading the compositions either onto an Percent Of the Welght of the e e 1n the mp l acceptable surface or support as above set out using h the greater the eeneentlatlen 111 the aqueenS eehla squeegee or doctor blade of by reverse roll coating." the greater t mount of carbonates that must be The compositions can also be used, for example, for used, and epreedlhg the 'eolhpesltloh Into films p y coating the back of carpets, for wall coverings that can 1113011 a pp material e known manner and breathe, for intermediate layers in floor coverings made ting the resultlng film or coating at an elevated temperb h calendaring process, or as l i ro a ature. for bottles. In the e 0f t Polyvmylehlondee as used hitherto A more comprehensive understanding of the invention n the fahrleeeatlng e e of flew t the Slewcan be obtained by referring to the following illustrative ness of the increase in viscosity caused a skm to form examples hi are not i d d however, to be on the surface which to a great extent prevented the d l li i i f the i i emergence of the water vapor and thus resulted in non- A uniform bubble formation in the sheet. But in the case EX MPLE of the polyvinylchlorides as used according to the inven- Sheets were. Produced y casting mllhmetel'jthlek tion the viscosity increases rapidly and no skin forms on layers of a mlXture havlng the following eomposltlehi the surface during the evaporation of the water, so that 100 parts of PVC E-69 the water vapor escapes readily. In this manner, non-uni- 100 parts of dioctylphthalate form bubble formation is prevented and a finely porous 1 part of nonylphenolpolyglycol ether sheet is produced. 4 parts of epoxidized soybean oil The following table represents a comparison of the with the following variations. viscosity increase and the packed densities of the varit t ous types of polyvinylchlorides. In part (a) of the table i wa er t (2) W1th 20 parts of water the types of polyvinylchlorldes customarily used in fabo 3 20 t f 10 t s 1 f ric-coating are set out while in part (b) the polyvinyl- CO par 8 0 percen aqueous o u Ion 0 chloride compositions according to the invention are set Out. 1 All parts are parts by weight.

TABLE 2 Time reqdtor Grain increasein Packed sizes, viscosity, densities, PVC (tradename) Manufacturer microns min. g./ml.

Part (a):

Hostalit PVP Farbwerke Hoechst 0. 2-5 24 0. Geon 121 Goodrich, U.S.A 0.2-5 24 0.42 Breon 121 British Geon 0.2-5 17 0. 39 Vinnol P-100/70 Wacker-Chemie 0.2-5 15 0.38 Vestolit E7001 Chemische Welke Huls.-. 0.2-5 14 0. 43 Vcstolit B7021 ..do 0. 2-5 9. 5 0. 33 Part (b):

combination with water, results in a reduction of viscosity however the nature of the viscosity reduction is not of the kind that is desirable for coating fabrics with doctor blades and the like.

In accordance with the invention those plasticizers can be used which are customarily used with polyvinylchloride, such as for example phthalic acid, sebacic acid, fumaric acid ester and/ or phosphoric acid ester.

The polyvinylchlorides used according to the invention can be either homopolymers or copolymers obtained using vinyl acetate, vinyl propionate, vinylidene chloride, and acrylic acid and/ or methacrylic acid derivatives, for example.

Chalk, cellulose, kaolin, asbestos, titanium dioxide and other known pigments can be added, for example, as fillers.

The mixture was allowed to set in a drying cabinet at a temperature of from to C.

From Table 1, which follows, it can be seen that the addition of ammonium carbonate has little or no influence on the density of the sheet produced from the mixture, and that for the most part it results in an opening of the pores, as shown in detail below.

Parts Ivory black 1 China clay X-1 40 10 percent aqueous ammonium carbonate solution 20 and a further mixture containing, in place of the ammonium carbon-ate solution, the corresponding amount of water, had the following viscosities as measured in the Haake Viskotester (Mfr.: Haake, Medingen), Mod. VT-23, with the spindle E-1000, at 5.8 r.p.m.

Poises Ammonium carbonate solution 600 Water 30,000

A mixture of the above composition was applied by spreading onto linen at the rate of 450 g./m. From Table 2 the effect of amonium carbonate on the perme ability of supported artificial leather can be seen. The table also shows that poor permeability is obtained by the addition of solid amonium carbonate.

TABLE 2 Air Ink permeability perme- PVC, type Additive l./h./100 cm. ability 0 do 0 0 PVC E69 Aqueous (NH4)2C03 620 2 PVC E-(SQ Solid (NHOZCOQ 10 1 1 The air permeability was measured at a pressure of 100 millimeters of water column.

EXAMPLE 3 A mixture having the following basic composition:

Parts PVC E-69 100 Dioctyl phthalate 90 Nonylphenol polyglycol ether 2 Epoxidized soybean oil 4 Ivory black 0.5

following the addition thereto of various amounts of aqueous ammonium carbonate and China clay was spread upon linen and tested for permeability. The coating as applied weighed 450 g./m.

In Table 3 there are set out the air and ink permeabilities obtained. The table indicates that the addition of a 5 percent ammonium carbonate solution does not result in any air or ink permeability.

When leavening or pore forming agents such as azodicarbonamide or azoisobutyronitrile, which are known commercially as Porofores, are used in combination with water and PVC compositions of the type which are here shown as being particularly suitable, open-pore sheet materials are also obtained, however, the technically desirable reduction of the viscosities is entirel lacking. Table 4 which follows illustrates this fact.

A composition consisting of:

Parts PVC E-69 50 Dioctylphthalate 45 Nonylphenol polyglycol ether 1 Epoxidized soybean oil 2 Chalk 17 Ivory black 0.5

and the additional materials as shown in Table 4, were spread to form a sheet.

TABLE 4 Azoisobutyric acid Weight Air perme- Ink Water, nitrile, per sq. m., Density. ability, permeparts parts grams g./ml. 1./h./ cm. ability EXAMPLE 5 A mixture consisting of:

Parts PVC E69 1000 Dioctyl phthalate 900 Aqueous 15% solution of NH HCO 200 Nonylphenol polyglycol ether 20 Epoxidized soybean oil 40 Ivory black 10 China clay X-l 400 was applied with a steel spreader to a satin fabric having a weight of 200 g. per square meter. The weight of the coating amounted to 430 g./m. The setting of the mixture was carried out in a tunnel using in combination hot air infrared heating at to C., with a time of stay of 50 sec. The measured air-permeability of this material was 1540 l./h. per 100 cm. the ink permeability was 2.

EXAMPLE 6 A mixture consisting of:

Parts PVC E-60 500 Dioctyl phthalate 450 Aqueous 15% solution of (NH CO 100 Nonylphenol polyglycol ether 10 Epoxidized soybean oil 20 Ivory black 5 China clay X-l 200 was applied to fabric samples in the same manner as described in Example 5. The coating amounted to 560 g. per sq. m. The air permeability as determined on these specimens amounted to 1480 l./h. per 100 sq. cm.; the ink-permeability was 2.

EXAMPLE 7 The same procedure was followed as described in Example 6, but in this instance chalk was used as the filler instead of China clay. At a coating weight of 400 g./m. the air-permeability was determined to be 920 l./h. per 100 sq. cm., and the ink-permeability was 2.

What is claimed is:

1. A macro-porous polyvinylchloride sheet material having a density of about 0.6 to 0.9 gram per milliliter made by forming a mixture consisting essentially of polyvinylchloride particles prepared by emulsion polymerization having an average grain size of about 30 to about 100 microns and a packed bulk density of at least 0.5 gram milliliter, a plasticizer for said polyvinylchloride and an aqueous solution of ammonium carbonate or bicarbonate which is about a 2 to 15 weight percent solution wherein the carbonate or bicarbonate of said solution is present in said mixture in an amount of about 0.2 to 3 weight percent based upon the total solids in said mixture; spreading said mixture into the form of a sheet or film; and setting said mixture at an elevated temperature.

2. The product as claimed in claim 1 wherein said mixture has the following composition:

Parts Polyvinylchloride 1000 Dioctyl phthalate 450 Aqueous 15 percent solution of (NI-I CO 100* Nonylphenol polyglycol ether 10 Expoxidized soybean oil 20 Ivory black 5 China clay 200 3. The product claimed in claim 1 having an air per- 8 meability of at least about 1480 liters per hour per 100 square centimeters and an ink permeability of 2.

References Cited UNITED STATES PATENTS 2,809,398 10/1957 Stiehl et a1 26454 2,875,088 2/ 1959 Stiehl et a1. 26454 3,198,773 8/1965 Stololf 260-928 10 DONALD E. CZAJA, Primary Examiner D. J. BARRACK, Assistant Examiner U.S. C1. X.R.

" UNITED STATES PATENT OFFICE 69 CERTIFICATE OF CORRECTION Patent No. 3520 Dat d July 21, 1970 Inventor(s) PAUL SPIELAU It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r" Column 1, line 9, "D 44,531" should be -D 49,531;

column 1, line 57, "aziosobutyronitrile" should be --azoisobutyronitrile--; column 3, Table 2, under the heading "Manufacturer" (5th item) "fi l should be --Huls-- column 4, line 9, "of" should be----or--; column 4, line 70, "compositions" should be --composition--; column 5, line 19, "amonium" should be --anmonium-; column 5, line 20, after "carbonate" insert --in absence of water-- Attest:

Edward M. Fletch. IR mm m mm, m Amsting ()ffi Gomnissionar of Patents 

